1. Field of the Invention
This invention relates to a device for use in splitting and breaking rock from inside of a predrilled hole. More specifically, this invention is directed to a borehole impact rock breaker that utilizes impact pins which extend from the device in order to transfer energy from a percussion hammer into a rock formation.
2. Description of Related Art
Existing devices designed to split and break rock from the inside of a predrilled borehole fail to utilize the efficiency and increased breaking ability of a rapidly striking pin. Instead, known in-hole rock splitters apply force to the inside of the borehole by exerting pressure, generally through the use of hydraulics, against a center piston which then spreads out wedges or cheeks which push against the rock formation. Such devices are described in U.S. Pat. No. 4,571,002 and U.S. Pat. No. 3,995,906, the entire contents of which are incorporated by reference herein. Newton's second law of motion allows quantitative calculation of dynamics, with force defined as mass (weight)×acceleration (change in velocity). Known in-hole rock splitters which use a center piston pressed between spread plates, utilize tremendous pressure/mass to spread plates and wedges. However, these devices do not deliver a high amount of force to the rock because the mass is not complemented with adequate acceleration. Advances in hydraulic and pneumatic percussion hammers have made hammers which can generate tremendous force with hundreds of impacts per second both possible and economical. However, there are no known in-hole rock splitting devices which take advantage of the operation of these percussion hammers.